Aim: To ascertain young adults’ experience of alcohol-related collateral harm (ARC harm).Methods: An online survey collected quantitative and qualitative data from a convenience sample of students (N = 450) aged 16–24 in Southern England. Questions and analyses focused on harms they had experienced as a result of alcohol consumption by other people in their family or social circle.Findings: Sixty-four percent of the participants experienced ARC harm, including 50% of non-drinkers. In logistic regression analysis, ARC harms were associated with being female (OR = 1.62, 95% CI 1.01–2.62) family members who drank every day (OR = 2.65, 95% CI 1.49–4.69) being influenced by others’ drinking (OR = 2.03, 95% CI 1.32–3.10) being older (OR = 2.61 95% CI 1.57–4.34). No significant associations were found with high or low self-reported levels of alcohol consumption. Using qualitative descriptors, the ARC harms reported were classified into a novel taxonomy comprising eight categories: nuisance/frustration/exasperation, tolerance/adjustment/accommodation, pressure into unwanted situations, unsought/inappropriate responsibility, psychological harm, physical harm/acute risk of physical harm, relationship harm, and undisclosed harm.Conclusions: A high level of ARC harm was reported and experience of ARC harm was linked to several predictors. Further work is required to validate the proposed taxonomy, and to promote consideration of the phenomenon of ARC harm in alcohol policy. [ABSTRACT FROM PUBLISHER]